Remove machine head bushings from a stepped hole?

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by Multi Angle Vise, Aug 7, 2018.


  1. Multi Angle Vise

    Multi Angle Vise Member

    Messages:
    183
    Joined:
    Apr 8, 2011
    I wish to replace a broken Kluson style machine head with a new machine head.

    The new machine head looks the same and matches the headstock screw holes, but it has a 6mm shaft instead of a 1/4" shaft, it's a wee bit sloppy. I am considering replacing the bushing as well, but have stumbled:
    • The old bushing is in a stepped hole. I cannot press the bushing from behind, there's only a ~1/4" (bit bigger) hole at the rear.
    • I wonder about finish adhering to the bushing?
    The answer might be well be to obtain a matching machine head with a 1/4" shaft.


    However, if you had to remove a bushing from a stepped hole cleanly, what are your tricks?


    Thanks!


    Edit: maybe this technique with a 1/4" inch drill shaft (or just over) that closely fitted the hole?

     
    Last edited: Aug 7, 2018
  2. Rhomco

    Rhomco Silver Supporting Member

    Messages:
    1,459
    Joined:
    Jul 23, 2005
    Location:
    Burleson, Texas (DFW)
    I would recommend back drilling/boring the 1/4 hole from the back side of the headstock enough to force the ferrule out with a proper stepped bushing install/removal tool.
    Rob
     
  3. wox

    wox Supporting Member

    Messages:
    856
    Joined:
    Jan 22, 2015
    Heat the bushings with a soldering iron and use a bit of the circular motion shown in the video.
     
    hank57 likes this.
  4. korus

    korus Member

    Messages:
    695
    Joined:
    Mar 20, 2007
    I understand that the hole from the back might be IDEALLY, EXACTLY the same size as inner diameter of the old bushing that is in the hole, but my experience is that you can actually put a flat screwdriver in the hole from the back of the headstock at angle, position the tip on the bushing and use minimal force knocking the screwdriver GENTLY with a hammer to lift a bushing on one side just a tiny bit, then do the same on the opposite side of the hole/bushing inside the hole, until you make a tiny gap underneath the bushing inside the hole, then put a screwdriver tip in that gap and repeat on both sides in these tiny baby steps. Repeating this will at some point release the bushing from the hole.

    Knocking gently, baby steps.
     
  5. Multi Angle Vise

    Multi Angle Vise Member

    Messages:
    183
    Joined:
    Apr 8, 2011
    Thanks guys for your thoughts!

    I might if it were another guitar, but it's probably my only guitar I feel compelled to preserve as close to factory as possible. I'll try and not remove wood yet...


    I'll give these a go first, and I take your point about catching the edge of the bushing at an angle.


    Appreciate it!
     
  6. walterw

    walterw Gold Supporting Member

    Messages:
    32,838
    Joined:
    Oct 16, 2006
    what's the guitar and what's the replacement key? why not just get the right key so it fits without all this drama?
     
  7. Multi Angle Vise

    Multi Angle Vise Member

    Messages:
    183
    Joined:
    Apr 8, 2011
    80s FujiGen LP. Original tuner looks like period Gotoh SD90 equivalent.

    Replacement tuner is modern Gotoh SD90. Modern SD90s have either a 6mm or 1/4" shaft depending on the post option. Bushing is 8.8mm OD regardless. https://g-gotoh.com/international/wp-content/uploads/2016/01/SD-post-dimension-1.jpg

    Already an SD90 set in the larder, hence attempting to use one of them first, no spending.



    Saw the stepped bushing hole, thought "There's probably a clever trick for a clean controlled extraction that I'm unaware of", thus this thread (say that three times). Curious about how others do it, as it wasn't immediately obvious to me. It's just a bushing.



    Another thought is adhesive lined heatshrink over both jaws of tiny circlip pliers, to grab the bottom edge of the bushing from the top, although the bushing wall may be a little too flexible.



    Upon receiving the circular tuit, I'll have a go. I shan't be expending any great effort. If the bushing comes out relatively easily, and if the replacement bushing fits the same hole, well and good. If either condition unsatisfied, buy a 1/4" shaft SD90. (Most of my guitars are consequence free environments, this one not so much.)
     
  8. PaulS60

    PaulS60 Member

    Messages:
    16
    Joined:
    Dec 5, 2012
    Could you thread the bushing with a tap, screw in a slug and press it out from the back?
     
    Mr Fingers likes this.
  9. Mr Fingers

    Mr Fingers Member

    Messages:
    789
    Joined:
    May 14, 2017
    Lots of chip/small damage potential. PaulS60's suggestion seems promising to me. Otherwise, the "small steps" pushing and levering is what I would do, hoping to observe any damage in the making before something chips.
     
  10. Rhomco

    Rhomco Silver Supporting Member

    Messages:
    1,459
    Joined:
    Jul 23, 2005
    Location:
    Burleson, Texas (DFW)
    Actually the tap is a quite ingenious suggestion from PaulS60 . Leads me to suggesting a 1/4 In Easyout…..boom!
    Rob
     
  11. Multi Angle Vise

    Multi Angle Vise Member

    Messages:
    183
    Joined:
    Apr 8, 2011
    Interesting ideas! This time I wish to preserve the original bushing and the wood. If the bushing doesn't come out easily and undamaged, I will buy the 1/4" shaft Gotoh SD90. Many times previously I've been able to pull bushings out with my fingers unaided. This one needs a little more than fingers, but too much more and I'll leave it there. No point winning the battle to lose the war.

    (For the kids at home - the Easyout suggestion is a handheld thing only - I hope no-one would put an Easyout in a drill and then in a guitar bushing.)

    I view this thread now as a sort of a brain-storming thing, a hypothetical bushing removal. Thanks for the contributions!
     
    Last edited: Aug 11, 2018 at 3:13 PM
  12. walterw

    walterw Gold Supporting Member

    Messages:
    32,838
    Joined:
    Oct 16, 2006
    yep!

    i'll do that very thing with a #1 phillips bit that steps down from a 1/4" hex driver. the round part fits through while the hex part doesn't, stick it in the bushing, work the screwdriver around, the bushing will work its way up out of the hole.
    [​IMG]
    for the same bushing that's tight in a non-stepped hole (where you could push on it from the back) i'll use the same bit from the back gently tapped with a hammer.
     
    Multi Angle Vise likes this.

Share This Page